What is a content delivery network?
A content delivery network (CDN) is a network distributed and interconnected servers that deliver pages and other Web content to a user much faster, based on the geographic locations of the user. The goal is to distribute web content to provide high availability and high performance. The CDN has become critical component of modern web applications and today the majority of web traffic is served through CDNs, including traffic from major sites like Facebook and Amazon. It also provides protection to the site from malicious attacks.
Definition of Azure CDN from Microsoft Documentation:
Azure Content Delivery Network (CDN) offers developers a global solution for rapidly delivering high-bandwidth content to users by caching their content at strategically placed physical nodes across the world. Azure CDN can also accelerate dynamic content, which cannot be cached, by leveraging various network optimizations using CDN POPs. For example, route optimization to bypass Border Gateway Protocol (BGP).
How Azure CDN Works
CDN stores cached version of web content in multiple geographical locations called as points of presence or POP. For faster delivery of content, CDN minimizes the distance between the user and the server, by delivering the content from the server within its closest proximity. For example, when someone in Delhi accesses your website hosted anywhere in the world, it delivers the website content from the India’s local POP, nearest to Delhi, which is much quicker than having the content travel the distances across world.
Azure CDN Features
Caching Rules to Control Azure CDN caching behavior:
Azure CDN provides two ways to control files caching:
- Caching rules: You define global caching rule for each endpoint in your profile, which affects all requests to that endpoint. This can be used to set default cache expiration behavior both globally and with custom conditions, such as a URL path and file extension.
- Query string caching: This allows you to define how the Azure CDN treats caching for requests with query strings.
Restricting content by country
You can restrict the access to your website content on the basis of country, the request is coming from. With the geo-filtering feature of Azure CDN, you are able to create rules on specific paths on your CDN endpoint to allow or block content in selected countries.
Azure CDN allows you to compress files to improve file transfer speed and increase application performance by reducing a file’s size. It helps you to reduce bandwidth costs and provide a responsive experience to users.
Limitations of Azure CDN
Azure CDN comes with some limits on each of below:
- Number of CDN profiles that can be created.
- Number of endpoints that can be created within a CDN profile.
- Number of custom domains that can be mapped to an endpoint.
For more information about CDN subscription limits, see CDN limits.